This invention relates to a variable speed motor control circuit, and more particularly to a circuit of this type utilizing a plurality of push button switches which are actuated momentarily and released to provide the desired speed of the motor being controlled.
There are a number of applications for motor control circuits to control the speed of a motor with a selection which may be as many as 15 or even more speeds, varying from very slow to very fast, for example, kitchen blenders, mixers, as well as many others where a number of variable speeds are required. In many such applications, a plurality of push buttons are utilized which, when activated, remain in that position until a predetermined period of time as set by a timer or until the device is switched off. In order to change speeds in such an arrangement, another push button must be depressed, and some mechanical linkage must be provided for releasing the previously activated button, requiring somewhat complex switching and mechanical arrangements to achieve the variable speed function. It would be desirable to provide a variable speed motor control circuit where a plurality of speeds are provided in which the push buttons are required to be only momentarily depressed, eliminating the need for the force required to latch a push button down, and further eliminating the complex and expensive switching arrangements. It would also be desirable to operate a variable control circuit for an appliance such as a blender in a manner whereby the motor runs only at a speed selected when the button representing that speed is continuously depressed. It would also be desirable to be able to combine the function of momentary depressing of a push button to obtain a given speed control as well as being able to depress a button continuously for maintaining a selected speed control, and also to provide a timer for the motor control circuit which would automatically stop the motor after a push button is momentarily depressed, maintaining the speed desired for the period of time desired.
Accordingly, it is an object of this invention to provide a new and improved multiple mode variable speed motor control circuit which can be run at a predetermined speed by momentarily depressing a push button of the speed desired.
Another object of this invention is to provide a new and improved variable speed motor control circuit which may be operated at the desired speed when the push button representing that speed is continuously depressed.
Still another object of this invention is to provide a new and improved multiple mode variable speed motor control circuit which may be run at a selected speed for a predetermined time interval by the momentary actuation of a push button representing that speed.
A further object of this invention is to provide a new and improved multiple mode variable speed motor control circuit which is easy to operate, provides a plurality of operating speeds as well as a plurality of modes of operation, and which is relatively inexpensive.